Over the past three years I’ve fielded almost as many questions about amps as I have about mics. It seems that there’s a significant amount of misinformation about amps--as they apply to harmonica players or others plugging high impedance microphones into them--and I never cease to be amazed at the things I hear.

Considering my lack of electronics skills and background, I turned to the experts on amplification for harp players--Craig’s Music (817-599-8021) and the builder of the Sonny Jr., Gary Onofrio (203-777-7426)--and these guys have been taking me to school for a couple of years, explaining why some amps work well, some don’t, and how modifications can be made to make even the most unfriendly amp sound a little better or become more functional. I’ve tried many of these recommendations out, and some should be required before ever laying down your hard earned cash on the Fenders, Gibsons, or other guitar amps that harp players mistakenly think will work great for them right off the shelf.

A recent bit of conversation on Harp-L led to a request from Phil Lloyd for some of this information. It’s a topic volumes could be written (or spoken) about, but Phil’s asked for some basics. So based on what I’ve learned, here are a few pointers and tips that I hope will help. Consider this a primer. For more information, you should contact the pros--guys who work with harmonica players day in and out. Or call me and I’ll see if I can find an answer for you.

Let’s start with the concept behind 99% of amps. They are designed for guitar players. A guitar is nothing like a microphone. What a guitar player wants from an amp, especially extreme gain and treble options, are anathema to what a harp player wants. The exceptions to this rule, amps designed especially for harp players--the Sonny Jr. amp for example--are miniscule.

Many of the amps made in the ‘50s were very different from those of the ‘60s and later. The dearth of PA systems at that time meant these amps had to function for instruments and microphones, and they had inputs for each, the mic input featuring significantly reduced gain on the signal transmitted to the amp’s power section. These amps are much more harmonica friendly. However, they are also low on overall power, which makes many incompatible with current on-stage playing requirement (like competing with that guitar player’s volume). And like all vintage amps they are prone to collector’s prices and potential maintenance problems, which, when corrected, frequently completely change the tone of older amps. For example, replacing rotting filter caps or weak tubes can make an amp sound 100% different.

There’s no set of general rules regarding older amps--especially those made before 1965. The same two vintage amps, made the same year, will sound different because of the way they’ve been used. I got proof of this a few years back at the national vintage guitar show held here in the Dallas area every year. A dealer had a new, original Fender Vibroverb--the classic 2X10 amp made in the early sixties which guys like James Harman think are one of the best ever made for harp (only a couple of hundred were ever made, making this a very rare amp). This one was new in the box, and guess what--the speakers were stiff, the tubes were new, and the amp didn’t have the tone or headroom of an older Vibroverb, like the ones James uses. Think of old amps like shirts--that favorite of yours has probably been worn and washed frequently, and is a lot softer than it was when you first bought it.

Because of all the variables when dealing with older amps, I’m not a big fan of them, unless someone like Craig’s Music has gone through them to get them ready for the road, doing the preventive maintenance that’s absolutely necessary for gigging with vintage equipment. So that leaves us with everything made since the mid-60’s, the Fender black and silver face amps, Gibsons, Ampegs and others, as well as the new ones, re-issues and vintage copies of the earlier Bassman, Vibroverb, Bandmaster, etc.

Once again, just in case you missed this earlier point: These amps are made for guitar players. Harp players are not even considered when Fender builds its amps. Which means these amps come with very unfriendly components, like 12AX7 preamp tubes, solid state rectifiers (or none at all), master volume switches, gain knobs, and, of course, the reverb hooked into the "effects" channel, which also happens to be the one that will generate the most feedback.

But there are some ways you can deal with the primary issues facing most harp players--feedback, tone and having effects like reverb at your disposal. Let’s start with the "effects" channel. Stay away from it. Have your reverb or tremolo wired directly into the normal channel, which is set up to have the least amount of gain generated at the point of input. Think of gain as feedback; the more gain you have at the point the signal is transmitted to the amp’s power section, the more feedback problems you’ll have. In almost all amps, the #2 hole on the normal channel has the least amount of gain. So always try to work from the normal channel.

Now for the second rule. Work with your preamp tubes. Preamp tubes are directly tied to gain, and they can directly increase or decrease the gain/feedback. Each has a rating figure, and the higher the total from the preamp tubes, the more feedback problems you’ll have. I use the following chart:

• 12AX7--100
• 12AT7--70
• 12AY7--40
• 12AU7--17.

So if you’re amp has three 12AX7 tubes, the gain total is 300. Replace these with 12AY7 tubes, and the gain rating is 120, less than half of the 12AX7s, which means a lot less feedback. And a lot more headroom. You can also mix and match the preamp tubes, which helps you dial in different mics, both for tonal quality and to help minimize feedback. A JT-30 seems to work best with 12AY7s, where a mic with stronger output like a Shure 545 works better with AT and AU tubes. This kind of experimentation will allow you to truly customize your amp to a mic.

Third rule: The more volume you can get, the richer the tone. Running an amp on 3 is like "idling a Porsche," as a friend of mine once said. You need to have your amp on 5-7 to really hear what it will do, when the juice is flowing through the tubes and the amp is really running hot.

Now for rule four--use the rectifier tube to help adjust the overall wattage, so you can play the amp at 5-7, regardless of the gig. Obviously, an amp with a rectifier tube is preferred over one without, where the wattage is set internally and can’t be adjusted at random (which is one of the reasons solid-state amps don’t work well for harp--you can’t make the necessary changes that make the amp mic-friendly). Most amps work with 5Y3, 5U4, GZ34 and solid state rectifier tubes, and they set the maximum wattage accordingly, with 5Y3 the least and solid state the most. With an amp like the Sonny Jr., which also has all these wonderful drive train changes to set it up exclusively for harmonica players (and the only amp of this kind I know of), you can use different rectifier tubes to set the amp up for gigs with your acoustic trio, or your two guitar/bass/drums format, for almost any room, always playing the amp on 7, generating massive tone. The Sonny Jr. is the only amp I know which will work in almost all playing environments--no need to have five amps around to deal with whatever the gig requires. (Class A amps, which have the all the power tubes running hot simultaneously, will normally not require rebiasing when making tube changes. If your amp is A-B, where the power tubes alternate running hot--a piston-like effect--you’ll want to call the amp manufacturer or your tech to inquire about biasing. Class A amps are preferred for harp because they do run hot.)

Finally, a note on "boutique amps"--those so called expensive amps made by "custom" amp makers and usually costing in excess of $1,000. There are a lot of guys out there that seem to be claiming to make "harp amps", but I would always suggest that you ask the following questions before ever putting any of your hard-earned cash on the line:

1. What harp player was consulted in the design of the amp, and what is his background as a player (especially how often he plays out) and owner of amps?

2. What mics were used in the design of the amps.

3. How many classic harp amps were analyzed and used as the basis for the design of the amp?

4. Will the amp work in a variety of different gig situations--small room, large room, low volume, high volume? Or is it just a loud amp that will only work where volume is the primary consideration?

5. When was the amp design completed, the first amp produced, and what changes and improvements have been made to the amp since then, and why?

6. How available is the amp designer to you, the customer, if you have questions or problems?

My experience with many amp manufacturers is that the so-called "harp amps" they make are really designed to take advantage of what they perceive as a market, and are not the results of consultation with harmonica players, based on classic harp amps, and are rarely improved once they hit the market (in the last few years some have even come and gone, even though the harmonica world has grown immensely in that time--go figure). One of the reasons the Sonny Jr. is such a great amp is that Gary Onofrio can deal with everyone of the questions listed above, is available to his customers, a serious player, and he continually is working to improve the product, based on comments of guys like you and me, as well as the greats like Kim Wilson, Fingers Taylor and others.

Remember, the information herein is just a primer. But it should give you a good starting point in trying to get your amp running more to your liking.

Tom Ellis III is the owner of Tom’s Mics in Dallas. His band gigs weekly in the Dallas area.. He has lost a small fortune investing in amps that he quickly became disenchanted with. Then he bought a Sonny Jr. Call him at 214-328-3225 for more information, or e-mail to tomsmics@flexcomp.com

This article has been provided by Tom Ellis of Tom's Mics and is for your reading pleasure.  Reprints to paper and distribution require Tom's approval.

| Home | Search | Mailing List |

Harmonica MasterclassŪ Company Info or E-mail